Things are quickly changing when it comes to internet data
plans. While we were used to a plethora of unlimited data plans for our
smartphones and even our home internet connections, service providers are now implementing
bandwidth caps to curb data usage.

When it comes to smartphones, many users feel that that
should be able to use that data anyway they please, however, service providers
clearly don't feel the same way. For this reason, data tethering -- which
allows you to share your smartphone internet data connection with other devices
-- is usually a separate charge from your data plan.

Those that get around this extra fee by jailbreaking and
using "unauthorized" apps had better start watching your back --
AT&T is beginning to crackdown on users. According
to TUAW, AT&T is sending out letters to customers that it believes are
using unauthorized tethering solutions. Here's a snippet from the full text
(which can be found here):

Tethering
can be an efficient way for our customers to enjoy the benefits of AT&T’s
mobile broadband network and use more than one device to stay in touch with
important people and information. To take advantage of this feature, we require
that in addition to a data plan, you also have a tethering plan.

Our
records show that you use this capability, but are not subscribed to our
tethering plan…

If
we don’t hear from you, we’ll plan to automatically enroll you into DataPro 4GB
after March 27, 2011. The new plan – whether you sign up on your own or we
automatically enroll you – will replace your current smartphone data plan,
including if you are on an unlimited data plan.

If
you discontinue tethering, no changes to your current plan will be required.

One of the most popular apps for jailbroken iPhones is MyWi.
MyWi allows a user to tether their iPhone without payingthe additional monthly
tethering fee to AT&T. The app allows tethering via USB, Bluetooth, or
Wi-Fi and is available for a
one-time fee of $19.99.

The letter doesn't say how AT&T was able to determine
that the customer was tethering, but it stands to reason that grandfathered
unlimited data plan customers that are using multiple gigabytes of data per
month are prime suspects.

"This week I got an iPhone. This weekend I got four chargers so I can keep it charged everywhere I go and a land line so I can actually make phone calls." -- Facebook CEO Mark Zuckerberg